JP5497614B2 - Magnetic fluid (MR) attenuator, method for improving magnetic fluid (MR) damping force performance, and magnetic fluid (MR) damping system - Google Patents

Description

TECHNICAL FIELD The present invention relates to a ferrofluid (MR) attenuator for use in controllable damping applications, including an MR piston assembly having a main channel for wiring, and more particularly a main channel MR piston. A secondary channel is defined in the piston body of the assembly and is particularly low due to the length of the secondary channel from the groove defined in the piston body about the piston body axis to the first end of the piston body. Improve MR damping force performance at piston assembly speed.

BACKGROUND OF THE INVENTION Conventional piston attenuators include magnetic fluid (MR) attenuators. The MR attenuator has a cylinder in which MR fluid is contained. The MR piston is slidably engaged within the cylinder. The first end of the rod is attached to the MR piston and the second end of the rod extends out of the cylinder. The rod and cylinder are attached to two separate structures to inhibit or damp the relative movement of the two structures along the direction of movement of the MR piston. Damping force is generated in the cylinder of the MR attenuator as opposed to the movement of the rod and MR piston along the axis of the MR attenuator.

  The MR fluid consists of fine metal particles, a carrier fluid, and a stabilizer. Fine metal particles, such as iron, are suspended in the carrier fluid. The fine metal particles in the MR fluid have a size in the range of 0.1 to 10 micrometers and have a shape like an ellipse or a scale sphere when viewed with the human eye after being magnified. If the metal particles are too large, they can settle instead of being suspended in the MR carrier fluid. If the metal particle fluid is too small, the desired magnetic effect on the metal particles begins to decrease. A typical MR fluid consists of 20 to 40 volume percent fine metal grains relative to the MR carrier fluid. The carrier fluid in the MR fluid may be a kind of oil such as hydrocarbon oil, silicone oil or ester oil. Preferably, hydrocarbon oil is used in the MR fluid. Hydrocarbon oils have the desired high lubricity and are available in a wide range of viscosities. Stabilizers are additives in the carrier fluid that prevent gradual gravitational settling of metal particles. As the metal particles settle in the MR fluid, the stabilizer prevents the metal deposit from being compressed. When compression of the metal deposit occurs, it becomes difficult to remix the metal deposit and optionally return it to the MR fluid. Furthermore, a low vapor pressure for the MR fluid is desirable so that the MR fluid does not evaporate easily. MR fluids are adapted to operate over a wide range of temperatures.

  MR fluids exhibit fluid behavior that is selectively controlled when a magnetic field is applied. If no magnetic field is applied to the MR fluid, the fine metal particles are arbitrarily suspended in the MR fluid. When no magnetic field is applied, the MR fluid has a low viscosity and exhibits lubricity. When a magnetic field is applied to the MR fluid, the fine metal particles form particle chains in the MR fluid in units of milliseconds. The particle chains generally align with the flux direction of a given electric field. Due to the formation of particle chains, the MR fluid properties change from a liquid to a quasi-solid state, the viscosity increases and behaves like a viscoelastic material. When subjected to deformation, the viscoelastic material exhibits both viscous and elastic properties. Viscous materials resist shear flow and strain linearly with time when stressed. The elastic material is distorted as soon as it is pulled, but quickly returns to its original state when the stress is removed. An MR fluid that acts as a viscoelastic material when applied with a magnetic field exhibits both these properties. MR fluid exhibits time dependent strain characteristics.

  In MR damping operation, the MR fluid passes through the opening of the MR piston while the piston reciprocates in the cylinder. The MR fluid at the opening receives a fluctuating magnetic field generated by changing the current applied to an electrical coil located in the MR piston. A piston made of a metal soft magnetic material forms an electromagnet together with an electric coil. This electromagnet applies a magnetic field to the MR fluid in the cylinder. By applying a magnetic field, the fine metal particles in the MR fluid form chains at the openings, and these chains are generally aligned in the direction of the magnetic flux and perpendicular to the flow of MR fluid flowing in the piston. The chain of fine metal particles limits the movement of the MR fluid through the piston opening and increases the yield stress of the MR fluid. As the yield stress of the MR fluid increases, the MR attenuator force increases. As will be appreciated by those skilled in the art, the current applied to the electromagnet results in a variable force operating condition of the MR fluid at the variable piston speed of the MR attenuator. Therefore, the variable damping effect of the MR piston can be brought about. Due to the variable damping effect, variable control damping of the relative motion between the MR piston and the cylinder can be realized. The damping performance of an MR attenuator in a suspension system is highly dependent on the MR attenuator force versus piston assembly speed characteristics. The variable control damping performance of the MR attenuator can be measured and evaluated using damping force versus piston assembly speed curves.

US Pat. No. 6,612,409

  In accordance with prior art US Pat. No. 6,612,409 issued September 2, 2003, and referring to FIGS. 1-2, the MR attenuator (10) includes a cylinder (14 ) Including an MR piston assembly (12) having a main channel used for wiring. In the following, an MR piston assembly having a main channel for wiring is referred to as a “main channel MR piston assembly”. The MR fluid (16) is placed in the cylinder (14). The main channel MR piston assembly (12) includes a coaxial piston body (18). A coaxial annular structure (20) about the piston body (18) defines an annular substantially magnetically energizable MR fluid passageway (22). The piston body (18) further includes a first end (24) and a second end (26) that is axially spaced from the first end (24). The first end plate (28) is attached to the first end (24) and the second end plate (30) is attached to the second end (26). The piston body (18) defines a coaxial hole (32) therethrough. The piston body (18) includes a body outer surface (34). The piston body (18) defines a circumferential coil groove (36) about the axis A on the body outer surface (34). A main channel (38) is defined in the body outer surface (34) from the hole (32) of the second end (26) to the coil groove (36. The main channel (38) is the first main channel portion. (39) and a second main channel portion (39A) The first main channel portion extends from the second end (26) to the coil groove (36). 39A) is disposed at the second end (26) and extends from the hole (32) in the second end (26) to the first main channel portion (39), the conductor (40) being 2 is located in the hole (32) at the end (26) and passes through the main channel (38) into the coil groove (36), in which the electrical conductor (40) is electrically coiled (42). ) In the second end (26) hole (32), the main channel ( 8) and the coil groove (36) are filled with a non-magnetic material (44) to effectively seal the electrical conductor (40) and the electric coil (42) in. The coaxial rod (46) is the first. Is connected to and includes a coaxial opening (48) in which the rod (46) is connected to the piston body (18) via the retaining ring (35) at the first end (28). The opening (48) includes conductive means for supplying current to the piston body (18) via a conductor (40) and an electrical coil (42) A power supply external to the MR attenuator Conductive means (50) electrically connected to the power supply to the piston body (18) via the conductor (40) and the electric coil (42), the piston body (18) further comprising one or more Substantially non-energizable MR fluid passage (52) Or it may include a bypass hole, which is remote from axis A and starts from hole (32) MR fluid (16 through the cross section of magnetically energizable passage (22) and magnetic deactivatable passage (52) ) Is designed to meet the performance requirements of specific MR attenuator applications.

  The damping force versus piston assembly speed performance curve for the main channel MR piston assembly of the MR damper shows the MR fluid force data along the y axis and the main channel MR piston assembly speed data along the x axis. The damping force vs. main channel MR piston assembly speed curve is the force axis at the y-intercept value above zero when approaching from the positive speed side and at the y-intercept value below zero when approaching from the negative speed side. Cross the y-axis. The greater the difference between the y-intercept value above zero and the y-intercept value below zero, the greater the undesirably greater force increase between the finite positive value and the finite negative value. . For example, in a vehicle system in which an MR attenuator is used, the greater the undesired increase in force associated with each direction of movement of the main channel MR piston assembly, the greater the undesired ride comfort when riding in the vehicle. The value of badness increases. Undesirable discomfort when riding in a vehicle may feel negative to the vehicle occupant. Ideally, the damping force vs. main channel MR piston assembly speed performance curve through the origin (x = 0, y = 0) is desirable in order to reduce undesirable objectionable components that impair the smooth ride comfort of the vehicle.

  As shown in the prior art of FIG. 1, a single bypass hole (52) defined in the main channel MR piston assembly serves to lower the y-intercept point closer to the origin and at a lower main channel MR piston assembly speed. This can provide a smoother ride for any vehicle. However, the ramping ramp portion of the damping force versus main channel MR piston assembly speed curve following the y-axis intercept point generally includes at least two distinct ramp ramp segments, ie ramp steps. Each separate ramp step has its own positive and decreasing slope value. The second step results in a lower driving force between the step transition and the knee point. The two-step ramp ramp moves to the knee point and transitions to the desired performance curve, which is relatively gentle with increasing force values over the knee point over the medium to high main channel MR piston assembly speed. A right-upward diagonal line is shown.

  What is needed is an improved MR attenuator with a main channel MR piston assembly that reduces the two-step ramp ramp at low MR piston speeds and increases the driving force.

SUMMARY OF THE INVENTION In accordance with one embodiment of the present invention, a ferrofluid (MR) attenuator has a longitudinal axis. The MR attenuator includes a coaxial cylinder in which MR fluid is contained. The MR attenuator includes a main channel MR piston assembly that is coaxially disposed within the cylinder and adapted to slidably engage within the cylinder for axial reciprocation within the cylinder. . The main channel MR piston assembly includes a piston body that defines a coaxial bore therethrough. The piston body further includes a body outer surface, a first end, and a second end that is axially spaced from the first end. The first and second ends of the piston body are substantially perpendicular to the axis. The piston body further includes a first end plate connected to the first end and a second end plate connected to the second end. The piston body further includes a circumferential coil groove defined on the outer surface of the body about the shaft and a main channel defined in the outer surface of the body and extending from the hole at the second end to the coil groove. The piston body further includes a conductor disposed within the hole and the main channel, the conductor configured to form an electrical coil disposed in the coil groove. The piston body further includes a non-magnetic material that is configured to fill the hole in the main channel and the second end and that effectively seals the electrical conductor and the electrical coil. The main channel MR piston assembly further includes an annular structure that surrounds the piston body about the axis, is attached to the piston body, has a relationship parallel to the axis and spaced from the annular space. A magnetically energizable MR fluid passage is defined. The main channel MR piston assembly further includes a coaxial rod that defines a coaxial opening therethrough. The rod is attached to the first end plate. The opening of the rod is substantially aligned with the hole in the piston body at the first end. The opening includes conductive means electrically connected to the conductor. The improvement of the MR attenuator is in the secondary channel defined on the body outer surface of the piston body of the main channel MR piston assembly. The secondary channel extends from the coil groove toward the first end and is filled with a non-magnetic material. The main channel of the MR damper The secondary channel in the piston body of the MR piston assembly provides improved low speed MR damping force performance.

  In accordance with another embodiment of the present invention, a ferrofluid (MR) attenuator has a longitudinal axis. The MR attenuator includes a coaxial cylinder having an MR fluid disposed therein. The MR attenuator further includes a multi-main channel MR piston assembly that is coaxially disposed within the cylinder. The multi-primary channel MR piston assembly is adapted to slidably engage within the cylinder to allow axial reciprocation therein. The multi-primary channel MR piston assembly includes a piston body that defines a coaxial bore therethrough. The piston body of the multi-main channel MR piston assembly includes an outer body surface. The piston body further includes a first end and a second end that is axially spaced from the first end, the first and second ends being substantially perpendicular to the axis. The piston body further includes a first end plate attached to the first end and a second end plate attached to the second end. The piston body further includes first and second circumferential coil grooves defined on the outer surface of the body about the axis. The second circumferential coil groove of the piston body is closer to the first end than the first circumferential coil groove and is defined on the outer surface of the body around the axis. The second circumferential coil groove of the piston body does not overlap with the first circumferential coil groove of the piston body. The piston body further includes a first main channel defined in the outer surface of the body and extending from the hole in the second end to the coil groove. The piston body further includes a second main channel defined on the outer surface of the body and extending from the first coil groove to the second coil groove. The piston body further includes a conductor disposed in the hole, the first main channel, the first coil groove, the second main channel, and the second coil groove. The conductor is configured to form a first electric coil disposed in the first coil groove and a second electric coil disposed in the second coil groove. The piston body further fills the holes in the first coil groove, the second coil groove, the first main channel, the second main channel, and the second end, and the conductor and the first and second electrical grooves. A non-magnetic material configured to effectively seal the coil. The piston body further includes a secondary channel defined on the outer surface of the body and extending from the second coil groove toward the first end. The secondary channel is filled with nonmagnetic material. The multi-main channel MR piston assembly further includes an annular structure that surrounds and is attached to the piston body about the axis. The annular structure further defines a substantially magnetically energizable MR fluid passage having a relationship parallel to the axis and spaced from the annular space. The multi-main channel MR piston assembly further includes a coaxial rod that defines a coaxial opening therethrough and is attached to the first end plate. The opening of the rod is substantially aligned with the hole in the piston body at the first end. The opening of the rod includes conductive means electrically connected to the conductor. The secondary channel provides improved slow MR damping force performance.

  In accordance with a further embodiment of the present invention, a method is provided for improving low velocity ferrofluid (MR) damping force performance. The method includes providing an MR attenuator having a longitudinal axis. The MR attenuator has a coaxial cylinder in which the MR fluid is contained. The MR attenuator includes a main channel MR piston assembly that is coaxially disposed within the cylinder and is adapted to slidably engage within the cylinder for axial reciprocation therein. The main channel MR piston assembly includes a piston body that defines a coaxial bore therethrough. The piston body of the main channel MR piston assembly has a body outer surface. The piston body further includes a first end and a second end that is axially spaced from the first end, the first and second ends being substantially perpendicular to the axis. The piston body further includes a first end plate attached to the first end and a second end plate attached to the second end. The piston body further includes a circumferential coil groove defined on the outer surface of the body relative to the shaft. The piston body further includes a main channel on the outer surface of the body that extends from the hole at the second end to the coil groove. The piston body further includes a conductor disposed within the hole and the main channel. The conductor of the piston body is configured to form an electrical coil that is disposed in the coil groove. The piston body includes a non-magnetic material configured to fill the coil groove, the main channel, and the second end hole to effectively seal the electrical conductor and the electrical coil. The piston body further includes a secondary channel disposed on the outer surface of the piston body and extending from the coil groove toward the first end. The secondary channel is filled with nonmagnetic material. The main channel MR piston assembly includes an annular structure that surrounds and is attached to the piston body relative to the axis. The annular structure of the main channel MR piston assembly defines a substantially magnetically energizable MR fluid passage having a relationship parallel to the axis and spaced from the annular space. The main channel MR piston assembly further includes a coaxial rod that defines a coaxial opening therethrough. The rod is attached to the first end plate, the coaxial opening in the rod is generally aligned with the hole in the piston body at the first end, and the opening includes conductive means electrically connected to the electrical conductor. The MR attenuator includes a damping force vs. main channel MR piston assembly speed performance operating range that is effective during operation of the MR attenuator. The primary channel and the secondary channel are effective in establishing the base performance curve of the MR attenuator within the performance operating range. The base performance curve has a first y-intercept value, followed by a single diagonal ramp ramp that generally rises to the right at low main channel MR piston assembly speeds. The single diagonal ramp ramp moves to the first knee point in the base performance curve. The first knee point is at the first main channel MR piston assembly speed. The first knee point transitions to a generally gentle upward sloping ramp on the base performance curve. A gentle upward sloping ramp ramp spans the medium to high main channel MR piston assembly speed.

  In accordance with a further embodiment of the present invention, a ferrofluid (MR) attenuation system includes a controller and at least one MR attenuator electrically connected to the controller, the controller operatively controlling the operation of the MR attenuator. To do. The at least one MR attenuator has a longitudinal axis. The MR attenuator has a coaxial cylinder in which the MR fluid is contained. The MR attenuator includes a main channel MR piston assembly disposed coaxially with the cylinder and adapted to slidably engage within the cylinder for axial reciprocation within the cylinder. The main channel MR piston assembly includes a piston body that defines a coaxial bore therethrough. The piston body includes a body outer surface, a first end, and a second end that is axially spaced from the first end. The first and second ends of the piston body are substantially perpendicular to the axis. The piston body further includes a first end plate attached to the first end and a second end plate attached to the second end. The piston body further includes a circumferential coil groove defined on the outer surface of the body with respect to the shaft and a main channel defined in the outer surface of the body and extending from the second end hole to the coil groove. The piston body further includes a conductor disposed in the hole and the main channel and is configured to form an electrical coil disposed in the coil groove. The piston body further includes a non-magnetic material configured to fill the main channel and hole at the second end to effectively seal the electrical conductor and the electrical coil. The MR attenuator includes a secondary channel defined on the outer surface of the piston body of the main channel MR piston assembly. The secondary channel extends from the coil groove toward the first end and is filled with a non-magnetic material. The main channel MR piston assembly substantially surrounds the piston body about the axis and defines a substantially magnetically energizable MR fluid passage attached to the piston body and having a relationship parallel to the axis and spaced from the annular space. And an annular body. The main channel MR piston assembly further defines a coaxial opening therethrough and includes a coaxial rod attached to the first end plate. The opening of the rod is substantially aligned with the hole in the piston body. The opening includes conductive means electrically connected to the conductor. A primary channel MR piston assembly having a secondary channel defined in the piston body improves MR damping system performance at low primary channel MR piston assembly speeds.

  The invention will be further described with reference to the accompanying drawings.

1 is a longitudinal cross-sectional view of a prior art ferrofluid (MR) attenuator that includes a main channel MR piston assembly that is disposed within a cylinder containing MR fluid and that includes a piston body. FIG. FIG. 2 is a prior art piston body included in the main channel MR piston assembly of FIG. 2 is an image of the piston body of the present invention showing a primary channel, a secondary channel, and a substantially magnetically deactivatable MR fluid passage. FIG. 4 is a longitudinal cross-sectional view showing details of an MR attenuator piston and rod assembly comprising a main channel MR piston assembly including the piston body of FIG. 3. FIG. 4 is a cross-sectional view showing details of the secondary channel of the piston body of FIG. 3. FIG. 4 is an enlarged view showing a main channel and a secondary channel of the piston body of FIG. 3. FIG. 5 is a substantially magnetically energizable MR fluid passage of the main channel MR piston assembly of FIG. FIG. 4 is a graphical representation of mathematical model data of damping force versus main channel MR piston assembly speed curve for various piston assemblies. FIG. 6 is a graph illustrating the relationship between flux density per unit in the middle gap of a magnetizable MR fluid passage versus distance from the center of the main and secondary channels for various channel widths according to the present invention. FIG. 6 is a graph showing measured damping force versus piston velocity for a main channel MR piston assembly with a bypass hole and a main channel MR piston assembly with a secondary channel and no bypass hole. Graph showing damping force versus main channel piston assembly velocity curve for the number of substantially magnetically deactivatable MR fluid passages disposed in the main channel piston assembly for the main channel MR piston assembly including the secondary channel of FIG. FIG. FIG. 4 is a graph illustrating the damping force vs. main channel piston assembly speed curve of the main channel piston assembly of FIG. 4 and a plurality of other damping force vs. main channel piston assembly speed curves electronically implemented by the controller in accordance with an alternative embodiment of the present invention. FIG. FIG. 6 is a longitudinal cross-sectional view of a multi-primary channel MR piston assembly including secondary channels and details according to an alternative embodiment of the present invention. FIG. 5 illustrates an MR attenuation system including the MR attenuator of FIG. 4 in accordance with an alternative embodiment of the present invention. FIG. 5 illustrates a suspension system in a vehicle including the MR attenuator of FIG. 4 in accordance with an alternative embodiment of the present invention. FIG. 7 shows a piston body having a secondary channel that is axially aligned and offset with respect to the main channel, in accordance with an alternative embodiment of the present invention. FIG. 6 shows a secondary channel located in the piston body that is not axially aligned with the primary channel, in accordance with an alternative embodiment of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS In accordance with a first embodiment of the present invention and referring to FIGS. 3-7, MR attenuator 110 has a longitudinal axis A ′. The attenuator 110 includes a coaxial cylinder 114. Cylinder 114 has MR fluid 116 therein. The fluid 116 may be any type of MR fluid known in the art used in MR type attenuators. A circumferential MR piston assembly having a main channel for wiring, i.e., a main channel MR piston assembly 112, is coaxially disposed within the cylinder 114. The cylinder 114 and the main channel MR piston assembly 112 can be made of a variety of sufficiently rigid materials such as steel, aluminum, metal, metal alloys, composite materials, and the like. The assembly 112 is adapted to slidably engage within the cylinder 114 to allow axial reciprocation. To ensure slidable engagement, the assembly 112 has approximately the same diameter as the cylinder 114.

  Assembly 112 includes a piston body 118 that defines a coaxial bore 132 therethrough. The piston body 118 may be made of low carbon steel or similar soft magnetic material. One skilled in the art will appreciate that the nature of the fluid 116 and the components of the assembly 112 can be varied without limiting the operating range of the present invention.

  The hole 132 is typically formed by a drilling operation. Although the piston body 118 is typically a cylindrical solid, the piston body may take other forms without limiting the operation of the present invention. The diameter of the main body 118 is smaller than the diameter of the cylinder 114. The main body 118 includes a main body outer surface 134. The body 118 further includes a first end 124 and a second end 126 that is axially spaced from the first end 124. Ends 124 and 126 are generally perpendicular to axis A '. The body 118 further includes a first end plate 128 adjacent to the first end 124 and a second end plate 130 adjacent to the second end 126.

  A circumferential coil groove 136 is defined in the main body outer surface 134 about the axis A ′. As shown in FIG. 3, the circumferential coil groove 136 is approximately half the distance between the first end 124 and the second end 126 and is substantially perpendicular to the axis A ′. Alternatively, the coil groove 136 may be arranged in an orientation other than an orientation perpendicular to the axis A ′ at a distance other than half between the first end and the second end. The main channel 138 extends from the hole 132 in the second end 126 toward the coil groove 136 and is defined in the body outer surface 134. The main channel 138 includes a first main portion 139 and a second main portion 139A. The first main channel portion 139 extends from the second end 126 to the coil groove 136. Second main channel portion 139 A extends from hole 132 at second end 126 and is aligned with first main channel portion 139. The coil groove 136 and the main channel 138 can be formed in the body outer surface 134 by machining the body outer surface 134 or spreading the material with a reamer. The conductor 140 is disposed in the hole 132 at the second end 126. The conductor 140 is made of a metal material suitable for sending current, preferably copper. The conductor 140 passes through the main channel 138 and is wired in the coil groove 136. The conductor 140 is further configured in a coil groove 136 to form an electric coil 142. The electric coil 142 is disposed in the coil groove 136.

  Non-magnetic material 144 is configured to fill main channel 138 and hole 132 in second end 126. The non-magnetic material 144 effectively seals the conductor 140 and the electric coil 142 therein. The non-magnetic material 144 is insulative and is an electrically non-conductive material so as to prevent the coil and conductor from being electrically connected to the piston body. The non-magnetic material 144 prevents the conductor 140 and coil 142 from contacting the MR fluid 116 when the assembly 112 is disposed within the cylinder 114. Therefore, an undesired short circuit is prevented in the MR attenuator 110. The nonmagnetic material 144 may be formed from an overmold material. The overmold material is typically made of a polymer material.

  The annular flow velocity ring structure 120 substantially surrounds the body 118 about the axis A ′. The plates 128, 130 can be fixed and held against the piston body 118 by crimping the annular structure 120 onto the plates 128, 130. The annular structure 120 defines a substantially magnetically energizable MR fluid passage 122 having a relationship parallel to the axis A ′ and spaced from the annular space. The term “passage” means a passage through it. The substantially magnetically actuatable MR fluid passage is typically a cylindrical passage having a circular cross section. The substantially magnetically actuatable MR fluid passage may be formed in a linear or non-linear shape. The substantially magnetically actuatable MR fluid passage 122 has a length and the MR fluid 116 flows through the main channel MR piston assembly 112 in the cylinder 114 over that length in MR damping operation. The annular diameter of the substantially magnetically actuatable MR fluid passage is typically 20 to 40 millimeters. The length of the substantially magnetically energizable MR fluid passage 122 includes the respective openings of the first end plate 128 and the second end plate 130. MR fluid properties associated with the MR fluid 116 are electrically controlled in the substantially magnetically actuatable MR fluid passage 122 in MR attenuator operation. Alternatively, the substantially magnetically actuatable MR fluid passage is a substantially annular cylindrical passage having a flow cross-sectional segment of a substantially circular ring. The flow cross-sectional area of the substantially magnetically actuatable MR fluid passage 122 is substantially constant along the passage length.

  Coaxial rod 146 defines a coaxial opening 148 therethrough. The rod 146 is attached to the first end plate 128. The rod 146 is attached to the piston body 118 by press fitting into the body 118 and is held by a steel retaining ring 135 and a first end plate 128 that are held in place by the crimped flow velocity ring structure 120. The other end of the rod 146 away from the first end plate 128 is connected to a structure outside the MR attenuator. The opening 148 in the rod 146 aligns with the hole 132 in the body 118 at the first end 124. The opening 148 includes conductive means 150 that is electrically connected to the conductor 140. The current supplied to the conductor 140 can be supplied and controlled externally to dynamically regulate the damping force in the MR attenuator. For example, an external power supply or controller may be suitable to provide a variable current.

  As shown in FIG. 3, the substantially magnetic deactivatable MR fluid passage 152 allows the MR fluid 116 in the cylinder 114 to freely pass through the body 118 and the end plates 128, 130 during MR attenuator operation. Enable. A substantially magnetically deactivatable MR fluid passageway 152 is defined by a piston body 118, a first plate 128, and a second plate 130 therethrough. The first substantially magnetically deactivatable MR fluid passage 152 starts from the hole 132 and has a radial separation with respect to the axis A ′ in the axial direction. The substantially magnetic deactivatable MR fluid passage is typically linear, allowing MR fluid to flow freely through the piston body during MR attenuator operation. The substantially magnetically deenergizable MR fluid path is substantially unaffected by the applied magnetic field.

  The substantially magnetically deenergizable MR fluid passage 152 is known in the art as a non-magnetic fluid pressure bypass hole, or more simply as a bypass hole. It will be appreciated by those skilled in the art that the use of a bypass hole depends on the force performance required for the particular MR attenuator application. Further, the specific flow cross-sectional area of the magnetically deenergable passage is selected depending on the specific attenuator application. The radius of the center line of the substantially magnetically deenergizable MR fluid passage is typically 8 to 11 millimeters, the size of which depends on the intended use. The size of the substantially magnetically deenergizable MR fluid passage depends on the application of the MR attenuator.

A secondary channel 154 extends from the coil groove 136 toward the first end 124 and is defined in the body outer surface 134. Secondary channel 154 is filled with non-magnetic material 144. Material 144 prevents MR fluid 116 from flowing into secondary channel 154. This non-magnetic material of the secondary channel maintains the cross-sectional area of the substantially magnetically actuatable MR fluid passage and reduces the flux density on the secondary channel to the same extent as that of the main channel. is necessary. Thus, the combination of primary and secondary channels works in a manner similar to non-magnetic bypass holes. Referring to FIGS. 6-7, secondary channel 154 has a length L, a width W, and a depth D. As shown in FIG. 6, the length L of the secondary channel 154 extends from the coil groove 136 to the first end 124. The length L of the secondary channel can be an appropriate length depending on the performance requirements required for the MR attenuator. The length L extending from the coil groove 136 to the first end 124 is generally greater than the width W and the depth D.

  The first main channel portion 139 has a length L1, a width W1, and a depth D1 (not shown). Similar to the first main channel portion 139, the second main portion has a length L2, a width W2, and a depth D2. The width W1 and depth D1 of the first main channel portion 139 are substantially equal to the width W and depth D of the secondary channel 154, and further equal to the width W2 and depth D2 of the second main channel portion 139A. The uniform depth and width of the primary and secondary channels allow straight traveling uniform MR fluid to enter / exit substantially magnetically energizable MR fluid passages during MR attenuator operation. Typical widths of the primary and secondary channels are between 2 and 6 millimeters. The secondary channel depth D is typically about 1 to 4 millimeters. It will be understood that the present invention is not limited to a first main channel portion, a secondary channel, and a second main channel portion having substantially equal uniform thickness and uniform depth. For example, the secondary channel may have a greater width and depth relative to the corresponding width and depth of the first main channel portion. Different widths and depths used in different channels may give different bypass force characteristics. Referring to FIG. 6, the first main channel portion 139 and the secondary channel 154 are formed to have a quasi-rectangular cross-sectional shape. Alternatively, the first main channel portion, the secondary channel portion, and the second main channel portion may have other shapes such as a semicircle, a quasi-triangle, a quasi-trapezoid, and the like. Alternative embodiments may include a secondary channel having a different shape than the first main channel portion. Changing the shape of the channel may provide different force characteristics to better adjust the piston assembly for a particular application.

  Referring to FIG. 3, the main channel portion 139 and the secondary channel 154 are axially aligned with the axis A ′. Further, the main channel portion 139 is separated by the coil groove 136 and is axially aligned with the secondary channel 154. Alternatively, the primary channel portion and the secondary channel may be aligned in the axial direction, but the secondary channel does not extend completely to the first end. Referring to FIGS. 3 and 6, the width W1 of the first main channel portion 139 is aligned substantially axially with the width W of the secondary channel 139A. The width W 1 of the first main portion 129 is generally not shifted from the width W of the secondary channel 154.

  When not in operation, the assembly 112 is stationary in the cylinder 114 of the MR attenuator 110. Conductive means 150, conductor 140 and electrical coil 142 are not energized and no magnetic field is generated in MR fluid 116 in substantially magnetically energizable MR fluid passage 122. If no magnetic field is generated in the substantially magnetically energizable MR fluid passage 122, the metal particles remain arbitrarily suspended in the MR fluid 116. When not operating, the MR fluid 116 has a liquid characteristic behavior.

  In operation, the assembly 112 reciprocates in the cylinder 114 at a variable speed, and the force acting on the assembly 112 depends on the variable magnetic field applied to the MR fluid 116 in the substantially magnetically energizable MR fluid passage 122. The magnitude of the magnetic field depends on the amount of current applied to the electric coil 142 by the conducting means 150 via the conductor 140. The MR fluid 116 may be diverted to the bypass hole 152 that has substantially no magnetic field effect. Thus, the main channel MR piston assembly 112 may produce minimal damping force at lower main channel MR piston assembly operating speeds. This provides the “smooth” vehicle ride characteristics desired by vehicle occupants, for example in vehicle suspension systems.

  The performance of the operating main channel MR attenuator is understood by examining the damping force of the MR attenuator versus the main channel MR piston assembly speed curve. Referring to FIG. 8, a plurality of damping force versus MR piston assembly speed curves 160, 162, 164, and 166 are shown. Curves 160 and 162 represent the ideal operating performance of a prior art MR piston assembly without a main channel and a fluid pressure bypass hole, and a prior art MR piston assembly with a main channel without a bypass hole, respectively. Performance curves 164 and 166 represent the ideal operating performance of an MR attenuator with a primary channel and a secondary channel and no bypass hole, and an MR attenuator with a primary channel with a bypass hole, respectively.

  The ideal performance curve 160 of the main channel MR piston assembly has no non-magnetic fluid pressure bypass holes and no main wire slot channel, compared to the curve 162 with the main wire slot channel. Curve 160 has a y-intercept point at about y = 3,000 Newtons. The y-intercept point of curve 160 is typically followed by a single gentle upward sloping ramp ramp, or force shelf, at low, medium and high main channel MR piston assembly speeds. Curve 162 having the main wire slot channel has a y-intercept point at about y = 1,975 Newtons. The y-intercept point of curve 162 is followed by a substantially right-up ramp ramp that moves to the knee point at about x = 0.035 meters / second. The knee 162 of curve 162 is generally a single gentle upward slanted force shelf shown in curve 160 over the middle to high main channel MR piston assembly speed after a knee point at about 0.035 meters / second. Transition to. The high y-intercept force shown in the ideal performance curves 160 and 162 results in undesirable ride comfort when the attenuator speed passes through zero. In order to reduce this intercept, fluid pressure bypass holes are usually used.

  Curve 164 has a y-intercept point at about y = 300 Newtons. The y-intercept point of curve 164 is followed by a generally diagonally up-sloped ramp ramp that moves to the knee point at about x = 0.05 meters / second. The addition of a secondary channel at 164 significantly reduces the intercept force for curve 162 with only the primary channel. The knee point of curve 164 is generally a single gentle after a knee point at about x = 0.05, as shown for curves 160 and 162, over medium to high main channel MR piston assembly speeds. Transition to the right-upward diagonal power shelf. The main channel MR piston assembly of curve 166 includes a single non-magnetic fluid pressure bypass hole and has a y-intercept point at about y = 75 Newtons. The y-intercept point of curve 166 is followed by a substantially ramp-up single ramp ramp that moves to the knee point at approximately x = 0.08 meters / second. The knee point of curve 166 is approximately a single unit that is generally about 200 Newtons lower than the force shelf shown in curve 160 over a medium to high main channel MR piston assembly speed after a knee point at about 0.08 meters / second. Transitions to a gentle upward-sloping diagonal force shelf.

  In a vehicle suspension system comprising an MR attenuator that includes a primary channel MR piston assembly having a secondary channel, a lower y intercept point and an upward slope over the increased low speed range of the primary channel MR piston assembly that includes a secondary channel. A single diagonal ramp ramp is combined to provide improved vehicle performance. Although the secondary channel shown in FIG. 3 extends from the circumferential coil groove to the first end, the length of the secondary channel depends on the damping force vs. main channel MR associated with the main channel MR piston assembly. Associated with the y-intercept point of the piston assembly speed base curve. As the length of the secondary channel increases toward the first end, the damping force versus the y-intercept point of the main channel MR piston assembly base curve decreases correspondingly. By reducing the y-intercept point towards the origin of the damping force vs. main channel MR piston assembly base curve, an MR attenuator provides a “smooth” ride when used in a vehicle suspension system.

  The damping force versus main channel MR piston assembly speed curve of FIG. 8 for a main channel MR piston assembly including a secondary channel can be optimized depending on the application of use. For example, increasing the width W of the secondary channel 154 relative to the width of the substantially magnetically actuatable MR fluid passage 122, with respect to the corresponding knee point of the base damping force vs. main channel MR piston assembly speed curve, A damping force vs. main channel MR piston assembly speed curve is generated that provides a knee point at an increased main channel MR piston assembly speed on the operating curve. Referring to FIG. 9, for the flux density, in the middle of the fluid gap just above the primary or secondary channel, for a value for this ratio of 0.1 to 1.0, the gap length relative to the channel width. The effect of the ratio is shown. A distance of zero (0) refers to the center line of the channel (slot), where the flux density is minimal. One (1) distance is equal to the per unitized radial length of the magnetized MR fluid gap. The flux density increases as it approaches the end of the channel and approaches the nominal gap flux density of 1 per unit from the outer end of the channel. With this number, the level of gap flux density on the channel is controlled by the slot width corresponding to the gap length, the lower the gap / slot ratio, the lower the flux density. Bypass behavior is enhanced by reducing the flux density at the slot centerline as much as possible.

Referring to FIG. 10, a graph of measured damping force versus main channel MR piston assembly speed curves 170, 172 for a main channel MR attenuator including a secondary channel is shown. Curves 170, 172 are annular, substantially magnetically energizable MR fluids that include tapered ends at the first and second end plates that are MR fluid input / output points to the main channel MR piston assembly. Including passages. A primary channel MR piston assembly 112 that includes a secondary channel 154 that does not have a non-magnetic fluid pressure bypass hole is indicated by curve 170. The y-intercept point of curve 170 is about y = 500 newtons. A single diagonal ramp that goes up to the right follows the y-intercept point and moves to the knee point at about x = 0.4 meters / second. A zero velocity intercept of about y = 500 Newtons is approximately a single gentle, right-up diagonal power shelf over the medium to high main channel MR piston assembly speed after the knee point at about x = 0.04 meters / second. Transition to. In contrast, the curve is that of a single channel piston with a single bypass hole. The y-intercept point of curve 172 is at about y = 100 Newton, followed by a two-stage ramp that yields a knee point at x = 0.07 meters / second, past a knee point of about x = 0.07. Transition to a substantially single gentle upward sloping force shelf over medium to high main channel MR piston assembly speeds. The force shelf of curve 172 is lower than the force shelf of curve 174 by about 200 Newtons at about x = 0.27 meters / second. Overall, the use of secondary channels eliminates the hydraulic bypass holes, sees a significant force increase (+ 1000N) at lower speeds, and a further force improvement (+200) at higher speeds. This eliminates the force-velocity characteristic of the two slopes below the knee point. The disadvantage is that the zero speed intercept of this arrangement is slightly higher than that of the bypass hole, which is suggested by adding a very small fluid pressure MR fluid bypass hole or in FIG. As such, it can be improved by widening the primary and secondary channels.

  The damping force versus main channel MR piston velocity curve for a main channel MR piston assembly including a secondary channel can be further optimized depending on the number of bypass holes located in the main channel MR piston assembly. Referring to FIG. 11, the mathematical model curves 174, 176 and 178 are respectively a main channel MR piston assembly without a bypass hole, a main channel MR piston assembly with two bypass holes, and a main channel MR piston with three bypass holes. The assembly is shown. Increasing the number of bypass holes, as shown in FIG. 11, places the knee point position in the damping force versus main channel MR piston assembly curve at a higher main channel MR piston assembly speed on the x-axis. Increases the low edge speed response. Thus, the new damping force vs. main channel MR piston speed curve 172 and 174 and the corresponding knee point are rising to the right of the base damping force vs. main channel MR piston assembly speed curve 174, not including the bypass hole. . It will be appreciated by those skilled in the art that the knee point range of the curve is established depending on the number of bypass holes included in the main channel MR piston assembly. The required amount of bypass holes depends on the performance characteristics required for the MR attenuator application.

  Referring to FIG. 12, a further alternative embodiment of the present invention is a controller electrically connected to the main channel and secondary channel MR piston assembly (not shown) of the MR attenuator (not shown). Including the use of (not shown). The look table includes a plurality of values (not shown). The controller accesses these values and operably electronically controls the main channel MR piston assembly of the MR attenuator over the knee point operating range of the main channel MR piston assembly of the MR attenuator. In order to dynamically electronically control the force versus main channel MR piston assembly speed curve, no bypass holes are actually configured, or only very small bypass holes are configured in the main channel MR piston assembly. If a small bypass hole is required to achieve a lower y intercept point, the size of the small bypass hole is less than about 1.0 millimeter. The main channel and secondary channel MR piston assembly includes an initial damping force vs. main channel MR piston assembly velocity curve 180, with an initial y intercept point at about y = 150 Newtons, and about x = 0.3 meters / second. With some initial knee points. The data value represents a characteristic of at least one of a plurality of predetermined characterized damping force versus main channel MR piston assembly speed curves 182 and 184. At least one of a plurality of predetermined characterized damping force versus main channel MR piston assembly speed curves 182 and 184 is defined in the main channel MR piston assembly as shown in the embodiment of FIG. FIG. 6 represents at least one of a plurality of damping force versus main channel MR piston assembly velocity curves associated with at least one of the substantially magnetically deenergizable MR fluid passages. At least one curve of the plurality of damping force versus main channel MR piston assembly speed curves includes at least one y-intercept point of the plurality of y-intercept points and at least one knee point of the plurality of knee points. . The multiple knee points are at multiple primary channel MR piston assembly speeds. At least one y-intercept point of the plurality of y-intercept points is smaller than the initial y-intercept point of y = 150 Newton. At least one of the plurality of primary channel MR piston assembly speeds (about x = 0.2 meters / second and about x = 0.3 meters / second) is an initial primary speed of about x = 0.03 meters / second. Greater than channel MR piston assembly speed. The knee point operating range includes an initial damping force vs. main channel MR piston assembly speed curve 180 and at least one of a plurality of predetermined characterized damping force vs. main channel MR piston assembly speed curves 184, 182. Including. The controller may include a plurality of predetermined characterized damping forces versus the main channel MR piston assembly speed curve such that the initial damping force vs. main channel MR piston assembly speed curve defines the operation of the main channel MR piston assembly of the MR attenuator. At least one of the plurality of predetermined characterized damping force versus main channel MR piston assembly velocity curves is not selected and at least one curve of the main channel MR piston assembly of the MR damper is not selected. In order to define the operation, at least one of at least one of a plurality of predetermined characterized damping force versus main channel MR piston assembly speed curves is configured to be electronically selected. The selection of the curve by the controller occurs during the operation of the main channel MR piston assembly of the MR attenuator to optimize the performance of the main channel MR piston assembly at low main channel MR piston assembly speed. In the embodiment of FIG. 12, the knee point range introduced in the embodiment of FIG. 11 can be accessed without having to provide a plurality of bypass holes in the piston body. A single small bypass hole can be combined with the primary and secondary channels to combine and control the y intercept point, ie, the force intercept at zero velocity (meters / second). Thus, MR damping with a primary channel MR piston assembly including a secondary channel at low primary channel MR piston assembly speed by electronically controlling the attenuator force versus primary channel MR piston assembly speed curve over the knee point range in real time Dramatically increases the operating range of the vessel. Furthermore, compared to implementing a main channel MR piston assembly with actual bypass holes, degradation in the force shelf is not apparent at medium to high frequencies. This is because the attenuator performance limit is set by the base curve 180. Due to the actual absence of bypass holes in the main channel MR piston assembly, there is no degradation in the force shelf. The lookup table may be internal to the controller. Alternatively, the lookup table can be accessed from a remote location remote from the controller.

  Yet another embodiment of the present invention comprises a secondary channel that includes a first length from the coil groove toward the first end and a second length from the coil groove toward the first end. The second length is greater than the first length. The first length includes a first damping force versus main channel MR piston assembly speed curve having a first y-intercept point and a first knee point. The first knee point is at the first main channel MR piston speed. The second length includes a second damping force versus main channel MR piston assembly speed curve having a second y intercept point and a second knee point. The second knee point is at the second main channel MR piston assembly speed. The second y intercept point is smaller than the first y intercept point. The second main channel MR piston assembly speed is higher than the first main MR piston assembly speed, and the second knee point is the first and second damping force vs. damping force pair that draws the main channel MR piston assembly speed curve. To the right of the first knee point of the main channel MR piston assembly graph.

  In the embodiment of FIGS. 3-12, the main piston assembly is formed of a piston body that includes a main channel and a single secondary channel. An alternative second embodiment includes a piston body configuration that includes a plurality of primary and secondary channels or a dual coil piston assembly. In FIG. 13, where the elements in the embodiment of FIGS. 3-12 are numbered 100 differently, the MR attenuator (not shown) has two main channels for wiring. A dual coil piston assembly 213 is included. In the following, a dual coil piston assembly having two main channels for wiring will be referred to as a “multi-main channel MR piston assembly”. Multi-main channel MR piston assembly 213 has a longitudinal axis A ″. Assembly 213 is disposed in a cylinder (not shown) containing an MR fluid (not shown). Coaxially disposed within the cylinder and adapted to slidably engage within the cylinder for axial reciprocation therein The multi-main channel MR piston assembly 213 has a coaxial bore 232 therethrough. The piston body 219 includes a body outer surface 234. The piston body 219 further includes a first end 224 and a second axially spaced from the first end 224. An end 226. The first end 224 and the second end 226 are substantially perpendicular to the axis A ″. The first end plate 228 is attached to the first end 224 and the second end plate 230 is attached to the second end 226. The first circumferential coil groove 285 is defined on the main body outer surface 234 about the axis A ″. The second circumferential coil groove 286 is defined on the main body outer surface 234 about the axis A ″. The second coil groove 286 is defined in the outer body surface 234 around the axis A ″ and is closer to the first end 224 than the first coil groove 285. The second coil groove 286 is the first coil groove 286. The first main channel 287 defined in the body outer surface 234 extends from the hole 232 of the second end 226 to the first coil groove 285. The first main channel 287 is not overlapped with the coil groove 285. Includes a first main channel portion 288 disposed in the first coil groove 285 from the second end portion 226. The second main channel 289 is formed from the first coil groove 285 to the second coil groove 286. And is defined in the body outer surface 234. The conductor 240 is within the hole 232, the first main channel 287, the first coil groove 285, the second main channel 289, and the second coil groove 286. Conductive 240 is configured to form a first electric coil 290 disposed in the first coil groove 285 and a second coil groove 291 disposed in the second coil groove 286. The non-magnetic material 244 is formed. Is configured to fill the first coil groove 285, the second coil groove 286, the first main channel 287, the second main channel 289, and the hole 232 of the second end 230, and the conductor 240, effectively seals the first electrical coil 290 and the second electrical coil 291. A secondary channel 254 is defined in the body outer surface 234 and extends from the second coil groove 286 to the first end 224. Secondary channel 254 is filled with non-magnetic material 244. Annular structure 220 surrounds piston body 219 about axis A ″. Annular structure 220 is attached to piston body 219 and defines a substantially magnetically energizable MR fluid passage 222 having a relationship parallel to the axis and spaced from the annular space. Coaxial rod 246 defines a coaxial opening 248 therethrough. The rod 246 is attached to the first end plate 228 via the retaining ring 235. The opening 248 in the rod 246 includes conductive means 250 that aligns with the hole 232 in the piston body 219 and electrically connects with the conductor 240. Piston body 219 and first end plate 228 and second end plate 230 further define a substantially magnetic deactivatable MR fluid passage 252 therethrough. The substantially magnetic deactivatable MR fluid passage 252 is positioned to start from the bore 232 and is axial and axially spaced relative to the axis A ″. The piston body 219, structure 220 and assembly 213. Has substantially the same diameter width as the corresponding structure of the embodiment of FIGS. 3 to 12, but the axial length of each structure is greater than that of the embodiment of FIGS. The main channel portion 288, the second main channel 289, and the secondary channel 254 are aligned in the axial direction, and the first main channel portion 288 is aligned with the second main channel 289. The main channel portion 288 and the second main channel 289 further align with the secondary channel 254. The secondary channel 254 has a length L that extends from the second coil groove 286. Extending first end 224. Structure of the first embodiment of the assembly 113 described, designed and variations are applicable to the second embodiment of the assembly 213.

  As in the embodiment of FIGS. 3-12, the assembly 213 can be electrically connected to the controller as well. The controller accesses a look-up table containing values representing a plurality of damping force versus main channel MR piston assembly speed performance curves having distinct knee points in the MR attenuator knee point operating range. Dual coil pistons with multiple main channel MR piston assemblies are generally used when the length of the piston body is greater than the diameter of the piston body.

  As shown in FIGS. 4 and 13, the conductive means are copper wires 150, 250 that pass through rods 146, 246 and enter holes 132, 232 to connect with conductors 140, 240. Alternatively, the rod may include conductive means including electrodes (not shown) connected to a connector (not shown) protected by a seal, the connector being connected to an electrical connector on the piston body. The

  In a further alternative embodiment, the force performance of the main channel MR piston assembly including the secondary channel can be further optimized by increasing the cross-sectional diameter of the bypass hole. By increasing the cross-sectional diameter of the bypass hole, a new damping having a lower y-intercept point and knee point at a higher main channel MR piston assembly speed compared to the y-intercept point and knee point associated with the original bypass hole. Can result in a force versus speed curve.

  In a further alternative embodiment, the force performance of the main channel MR piston assembly including the secondary channel can be further optimized by setting the width of the main channel and the width of the secondary channel. The width of the secondary channel is approximately equal to the width of the main channel. The widths of the main channel and the secondary channel are related to the radial gap length of the substantially magnetically actuatable MR fluid passage, with respect to the length of the substantially magnetically actuatable MR fluid passage. And increasing the width of the secondary channel results in a new damping force versus main channel MR piston assembly performance curve. The new main channel MR assembly performance curve includes a second y-intercept point and a second knee point in the performance operating range of the MR attenuator. The second knee point is at the second main channel MR piston assembly speed. The second main channel MR piston speed is higher than the first main channel MR piston speed in the base damping force versus MR piston assembly speed curve. The second y-intercept point is lower than the first y-intercept point in the base damping force versus MR piston assembly speed curve.

  Referring to FIG. 14, a further alternative embodiment of the present invention includes a controller 395 that is in electrical connection with at least one primary MR attenuator 300 that includes the secondary channel described above. This circuit topology configuration may have application in motion equipment devices such as rowing machines and stair climbers that use shock absorbers to provide motion resistance. The number of MR attenuators required for use depends on the requirements of the device. A further alternative embodiment is to use MR attenuator 300 to provide motion isolation for buildings, bridges and other structures that are exposed to earthquakes. In yet another alternative embodiment, the MR attenuator 300 may be useful in vehicles and structures in space applications that have vibration damping requirements. Other uses are at the discretion of those skilled in the art.

  Another alternative embodiment of an MR attenuator can be used as a shock absorber in a suspension system for a device that includes wheels used for transportation. The haulage device can be an airplane, automobile, golf cart, motorbike, and other types of vehicles. In vehicle applications, an MR attenuator comprising a primary channel MR piston assembly that includes a secondary channel gradually reduces or completely reduces undesirable vehicle structure vibrations felt by vehicle occupants over the speed range of the assembly. Can be eliminated. Referring to FIG. 15, an MR suspension system is located in the vehicle, and a main channel MR attenuator 400 including a secondary channel is associated with each wheel 497 of the vehicle. The MR attenuator at each wheel is electrically connected to the controller 595, which includes a look-up table 496, and over the knee point range of the MR attenuator 400, a separate unique damping force versus MR piston for each wheel. Provide assembly performance curves. Thus, the unique suspension requirements for each wheel are met and an independent suspension system for the vehicle can be realized. The embodiment of FIG. 15 is an application of the embodiment of FIG. Alternatively, the controller uses the look-up table values to apply the same damping force versus MR piston assembly speed curve to the two front wheels, depending on the required damping needs of each wheel set, Different damping force versus MR piston assembly performance curves can be provided. In yet another embodiment, the controller can provide the same damping force versus MR piston assembly performance curve from a look-up table to all four vehicle wheels simultaneously.

  The present invention is not limited to a configuration in which the primary and secondary channels are aligned on the piston body as shown in the embodiment of FIG. 3 above. In some MR attenuator applications, it may be appropriate to arrange the secondary channel differently with respect to the primary channel in order to meet specific performance requirements. In yet another embodiment, referring to Figure 16, the main channel 539 and the secondary channel 554 are axially aligned with the longitudinal axis A "'through the piston body 518 and the rod 546. The main channel 593 and Secondary channel 554 is separated by circumferential coil groove 536. Primary channel 539 and secondary channel 554 are axially aligned, but secondary channel 554 is relative to axis A ″ ″. , Radially offset from the main channel 539. Accordingly, secondary channel 554 has an angle of rotation about axis A ″ ″ relative to main channel 539. The secondary channel extends from coil groove 536 to first channel on the outer body surface of piston body 518. Disposed to end 524. In a further alternative embodiment, referring to Figure 17, secondary channel 654 is spaced from axis A "" through piston body 618 and rod 646. Secondary channel 654 is , In an angled direction with respect to the axial direction, starting from the coil groove 636 and ending at the first end 624. Alternatively, starting at the coil groove and before reaching the first end of the piston body The secondary channel can be defined in the outer surface of the piston body with a configuration that ends in the coil channel from the coil groove toward the first end of the piston body or the first end. Up towards, it may take any arrangement in the outer channel surface of the piston body.

  Without being limited to a particular theory, inclusion of a secondary channel is believed to improve the performance of the primary channel MR piston assembly. Inclusion of secondary channels can eliminate or reduce the number of non-magnetic fluid bypass holes that have an undesirable impact on the force. It is particularly applicable to very low piston speeds where a large force is required for effective damping control. The primary and secondary channels are most effective when aligned axially to reduce breakaway force (force intercept).

  Theoretically, the length of the secondary channel is at the first end from the coil groove, and the other two channels other than the arrangement and length of the secondary channel that the main channel and the secondary channel are axially aligned. It is believed that the placement and length of the next channel will give the best results, which are lower than those described above. This best performance is reduced because the direction of MR fluid flow required for breakaway changes when the channels are not aligned.

  Several advantages and benefits are derived from the invention described herein. By defining the secondary channel in the piston body of the main channel MR piston assembly, the MR damping force performance at low main channel MR piston assembly speed is improved. Adding a secondary channel allows for a lower y-intercept point, followed by a single diagonal ramp ramp that rises generally to the right at a lower main channel MR piston assembly speed. A low y-intercept point and a substantially slanted ramp with a single ramp up to the right provide a higher driving force at lower attenuator speeds with a significant impact on vehicle handling. By adding a single bypass hole to the main channel MR piston assembly, it is possible to increase the low main channel MR piston assembly speed range or knee point while further reducing the y-intercept point. By using a secondary channel in the primary channel MR piston assembly, the need for multiple bypass holes to meet MR attenuation requirements in a particular application may be reduced. A controller in electrical connection with the main channel MR piston assembly can access a look-up table showing values representing characteristics of the main channel MR piston assembly including at least one of the plurality of bypass holes. This can improve dynamic performance operability without the need to actually implement a bypass hole in the main channel MR attenuator assembly.

  Although the invention has been described in terms of preferred embodiments, it is not limited to these embodiments. Various changes and modifications can be made without departing from the spirit and scope of the invention. For example, the main channel MR piston assembly including the piston body is not limited to a particular design, configuration, shape, size, or arrangement. Specifically, the substantially magnetically energizable passage, the substantially magnetic deactivatable passage (bypass hole), the opening of the rod and piston body, and the corresponding configuration, size, shape, geometry, position, orientation of these components And the number can be varied without limiting the utility of the present invention.

  A wide variety of other embodiments of the present invention are possible upon review of the specification and drawings, and it will be apparent to those skilled in the art that such embodiments are contemplated and fall within the scope of the claimed invention. it is obvious. The scope of the present invention is set forth in the appended claims, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

Claims (20)

A ferrofluid (MR) attenuator having a longitudinal axis,
A coaxial cylinder in which MR fluid is contained;
A main channel MR piston assembly, wherein the main channel MR piston assembly is coaxially disposed within the cylinder and is adapted to slidably engage within the cylinder for axial reciprocation within the cylinder. Includes a piston body defining a coaxial bore therethrough, the piston body including an outer surface of the body and a first end and a second end axially spaced from the first end; An end and a second end being substantially perpendicular to the axis, and a first end plate attached to the first end and a second end plate attached to the second end;
Around the axis, a circumferential coil groove defined on the outer surface of the main body,
A main channel defined on the outer surface of the body and extending from the hole at the second end to the coil groove;
A conductor disposed in the hole and the main channel and further configured to form an electrical coil disposed in the coil groove;
A non-magnetic material that fills the hole in the main channel and the second end and is configured to effectively seal the conductor and electrical coil therein;
An annular structure that substantially surrounds the piston body about an axis, is attached to the piston body and defines a substantially magnetically energizable MR fluid passage having a relationship parallel to the axis and spaced from the annular space;
Defining a coaxial opening therethrough, and including a coaxial rod attached to the first end plate, wherein the opening in the rod is generally aligned with a hole in the piston body at the first end, and the conductor and electrical Electrically conductive means for connecting,
The improvement comprises a secondary channel defined on the outer surface of the body of the piston body, said secondary channel extending from the coil groove towards the first end, wherein the secondary channel is made of non-magnetic material. An MR attenuator that is filled and provides improved low-speed MR damping force performance.   The MR attenuator of claim 1, wherein the secondary channel has a length that extends from the coil groove to the first end.   The main channel further includes a first main channel portion extending from a second end to the coil groove, the first main channel portion being axially aligned with the secondary channel. 2. The MR attenuator according to 2.   The MR of claim 1, wherein the main channel further includes a first main channel portion extending from a second end into the coil groove, the main channel portion axially aligned with the secondary channel. Attenuator.   The secondary channel has a first length from the coil groove to the first end and a second length from the coil groove to the first end, the second length being the first length. The first length includes a first damping force versus main channel MR piston assembly speed curve having a first y-intercept point and a first knee point, wherein the first knee point is a first length. The second channel includes a second damping force vs. main channel MR piston assembly speed curve having a second y-intercept point and a second knee point, the second channel Is at the second main channel MR piston assembly speed, the second y-intercept point is lower than the first y-intercept point, and the second main channel MR piston assembly speed is the first main MR piston assembly speed. Than speed And the second knee point is to the right of the first knee point on the damping force vs. main channel MR piston assembly graph depicting a first and second damping force vs. main channel MR piston assembly speed curve. The MR attenuator according to 1.   The main channel MR piston assembly includes a first substantially magnetic deactivatable MR fluid passageway, said first substantially magnetic deactivatable MR fluid passageway defined by a piston body and first and second plates therethrough. The MR attenuator of claim 1, wherein the first substantially magnetic deactivatable MR fluid passageway is disposed in a relationship starting from a hole and spaced axially away from the axis. .   The main channel MR piston assembly does not include the first substantially magnetic deactivatable MR fluid passage defining an initial damping force versus main channel MR piston assembly velocity curve having an initial y intercept point and an initial first knee point. The initial knee point is at an initial main channel MR piston velocity, and the main channel MR piston assembly includes the first substantially magnetic deactivatable MR fluid passage defining a first y intercept point and a first knee point. Wherein the first knee point is at a first main channel MR piston assembly speed, the first y intercept point is lower than the initial y intercept point, and the first main channel MR piston assembly speed is Higher than the MR piston assembly speed, the first knee point is the initial and first damping force versus main channel R piston assembly draws a velocity curve to the right of the initial knee-point on the damper force-versus-primary channel MR piston assembly graph, MR damper according to claim 6.   The main channel MR piston assembly includes a second substantially magnetic deactivatable MR fluid passageway, said second substantially magnetic deactivatable MR fluid passageway comprising a piston body and first and second plates passing therethrough. Wherein the second substantially magnetically deenergizable MR fluid passage starts from a hole and is disposed in an axially radial relationship with respect to the axis, the second substantially magnetically deenergized state The possible MR fluid path defines a second damping force versus main channel MR piston assembly speed curve having a second y intercept point and a second knee point, said second knee point being a second main channel MR piston. The second y-intercept point is lower than the first y-intercept point, and the second main channel MR piston assembly speed is equal to the first main MR piston assembly speed. Higher, the second knee point is the right side of the first knee point on the initial vs. first channel second damping force versus main channel MR piston assembly speed curve that draws the main channel MR piston assembly speed curve. The MR attenuator according to claim 7. The MR attenuator further
A controller in electrical connection with the main channel MR piston assembly of the MR attenuator;
A look-up table comprising a plurality of values, said values being placed in a look-up table and operatively driving the main channel MR piston assembly of the MR attenuator over the knee point operating range of the main channel MR piston assembly of the MR attenuator To control, the value is accessed by the controller,
The main channel MR piston assembly includes an initial damping force versus main channel MR piston assembly speed curve having an initial y intercept and an initial knee point, the initial knee point being at an initial main channel MR piston assembly speed;
The value includes a characteristic of at least one of a plurality of predetermined characterized damping force versus main channel MR piston assembly speed curves, wherein the plurality of predetermined characterized damping force versus main channel MR piston assembly speed curves. Said at least one curve of the plurality of damping forces associated with at least one of the plurality of substantially magnetically deactivatable MR fluid passages defined in the main channel MR piston assembly versus the main channel MR piston assembly. Representing at least one of the velocity curves, wherein the at least one of the plurality of damping force versus main channel MR piston assembly velocity curves is at least one of the plurality of y-intercept points and at least one of the plurality of knee points. And the plurality of knee points includes a plurality of main channel MR piston assemblies. At least one of the plurality of y-intercept points is lower than the initial y-intercept point, and at least one of the plurality of main channel MR piston assembly speeds is higher than the main channel MR piston assembly speed. ,
The knee point operating range includes the at least one of an initial damping force versus main channel MR piston assembly speed curve and a plurality of predetermined characterized damping force versus main channel MR piston assembly speed curves;
The controller is
In order to optimize the performance of the main channel MR piston assembly at the low main channel MR piston assembly speed during operation of the main channel MR piston assembly of the MR attenuator
(I) Of a plurality of predetermined characterized damping forces vs. main channel MR piston assembly speed curves such that the initial damping force vs. main channel MR piston assembly speed curve defines the operation of the main channel MR piston assembly of the MR damper And (ii) at least one of a plurality of predetermined characterized damping force versus main channel MR piston assembly speed curves is a main channel MR piston of the MR attenuator. Configured to electronically select at least one of at least one of a plurality of predetermined characterized damping force versus main channel MR piston assembly speed curves to define the operation of the assembly. The MR attenuator according to claim 1. A ferrofluid (MR) attenuator having a longitudinal axis,
A coaxial cylinder in which MR fluid is contained;
A multi-main channel MR piston assembly coaxially disposed within the cylinder and adapted to slidably engage within the cylinder for axial reciprocation within the cylinder; The piston assembly includes a piston body defining a coaxial bore therethrough, the piston body including a body outer surface and a first end and a second end axially spaced from the first end; A first end plate attached to the first end and a second end plate attached to the second end, the first end and the second end being substantially perpendicular to the axis; When,
A first circumferential coil groove defined on the outer surface of the main body around the axis;
A second circumferential coil groove defined on the outer surface of the main body around the shaft, the second coil groove being closer to the first end than the first coil groove and around the shaft Defined in the outer surface, the second coil groove does not overlap the first coil groove and further includes a first main channel defined in the outer surface of the body and extending from the hole in the second end to the coil groove; The first main channel includes a first main channel portion disposed in the coil groove from a second end;
A second main channel defined on the outer surface of the body and extending from the first coil groove to the second coil groove;
A hole, a first main channel, a first coil groove, a second main channel, and a conductor disposed in the second coil groove, the conductor being disposed in the first coil groove. 1 electrical coil and a second electrical coil disposed in the second coil groove, further configured to form a first coil groove, a second coil groove, a first main channel, a second A non-magnetic material that fills the primary channel and the second end hole and is configured to effectively seal the electrical conductor and the first and second electrical coils;
A secondary channel defined in the outer surface of the body and extending from the second coil groove toward the first end, the secondary channel being filled with a non-magnetic material;
An annular structure that substantially surrounds the piston body about an axis, is attached to the piston body, and defines a substantially magnetically energizable MR fluid passage having a relationship parallel to the axis and spaced from the annular space;
Defining a coaxial opening therethrough and comprising a coaxial rod attached to the first end plate, the opening of the rod being substantially aligned with the hole in the piston body at the first end and electrically connected to the electrical conductor Including conductive means to
An MR attenuator in which the secondary channel provides improved slow MR damping performance.   The first main channel portion, the second main channel, and the secondary channel are aligned in the axial direction, and the secondary channel has a length, the length from the second coil groove The MR attenuator of claim 10, extending to the first end.     The multi-main channel MR piston assembly includes a first substantially magnetic deactivatable MR fluid passageway, said first substantially magnetic deactivatable MR fluid passageway being defined by a piston body and first and second plates passing therethrough. 11. The MR attenuation of claim 10, wherein the first substantially magnetically deactivatable MR fluid passage is defined and starts in a hole and is disposed in an axially radial relationship with respect to the axis. vessel. The MR attenuator further
A controller in electrical connection with the multi-primary channel MR piston assembly of the MR attenuator;
A look-up table comprising a plurality of values, said values being placed in a look-up table and operating the multi-main channel MR piston assembly of the MR attenuator over the knee point operating range of the multi-main channel MR piston assembly of the MR attenuator The value is accessed by the controller to control automatically,
The multi-primary channel MR piston assembly includes an initial damping force vs. multi-primary channel MR piston assembly speed curve having an initial y-intercept point and an initial knee point, the initial knee point being at an initial multi-primary channel MR piston assembly speed;
The value includes a characteristic of at least one of a plurality of predetermined characterized damping force versus multi-main channel MR piston assembly speed curves, wherein the plurality of predetermined characterized damping force versus multi-main channel MR piston assembly. The at least one of the velocity curves may include a plurality of damping forces associated with at least one of the plurality of substantially magnetically deactivatable MR fluid passages defined in the multi-primary channel MR piston assembly versus the multi-primary. Representing at least one of the channel MR piston assembly speed curves, wherein the at least one of the plurality of damping force versus multi-primary channel MR piston assembly speed curves includes at least one of a plurality of y-intercept points and a plurality of knee points. Including at least one of the plurality of knee points. At least one of the plurality of y-intercept points is lower than the initial y-intercept point, and at least one of the plurality of multi-main channel MR piston assembly speeds is Higher than the channel MR piston assembly speed,
The knee point operating range includes at least one of an initial damping force versus multi-main channel MR piston assembly speed curve and a plurality of predetermined characterized damping force versus multi-main channel MR piston assembly speed curves;
The controller is
In order to optimize the performance of the multi-main channel MR piston assembly of the MR attenuator during operation of the multi-main channel MR piston assembly of the MR attenuator, at low multi-main channel MR piston assembly speeds,
(I) a plurality of predetermined characterized damping forces versus multi-main channel MR piston assembly speed such that the initial damping force vs. multi-main channel MR piston assembly speed curve defines the operation of the multi-main channel MR piston assembly of the MR attenuator; Not selecting at least one of the curves; and (ii) at least one of the plurality of predetermined characterized damping force versus at least one of the multi-main channel MR piston assembly speed curves is Electronically at least one of at least one of a plurality of predetermined characteristic damping force vs. multi-main channel MR piston assembly velocity curves to define operation of the multi-main channel MR piston assembly; Configured to select The MR damper according to claim 10. A method for improving ferrofluid (MR) damping force performance at low primary channel MR piston assembly speeds, comprising:
Providing an MR attenuator having a longitudinal axis, the MR attenuator comprising:
A coaxial cylinder in which MR fluid is contained;
A main channel MR piston assembly, wherein the main channel MR piston assembly is coaxially disposed within the cylinder and is adapted to slidably engage within the cylinder for axial reciprocation within the cylinder. Includes a piston body defining a coaxial bore therethrough, the piston body including an outer surface of the body and a first end and a second end axially spaced from the first end; An end and a second end being substantially perpendicular to the axis, and a first end plate attached to the first end and a second end plate attached to the second end;
Around the axis, a circumferential coil groove defined on the outer surface of the main body,
A main channel defined on the outer surface of the body and extending from the hole at the second end to the coil groove;
A conductor disposed in the hole and the main channel and further configured to form an electrical coil disposed in the coil groove;
A non-magnetic material that fills the hole in the main channel and the second end and is configured to effectively seal the conductor and electrical coil therein;
A secondary channel defined on the outer body surface of the piston body, the secondary channel extending from the coil groove toward the first end, the secondary channel being filled with a non-magnetic material; And an annular structure that substantially surrounds the piston body about the shaft, is mounted on the piston body, and defines a substantially magnetically energizable MR fluid passage having a relationship parallel to the shaft and spaced from the annular space; ,
Defining a coaxial opening therethrough, and including a coaxial rod attached to the first end plate, wherein the opening in the rod is generally aligned with a hole in the piston body at the first end, and the conductor and electrical Electrically conductive means for connecting,
The MR attenuator includes an initial damping force vs. main channel MR piston assembly speed curve that is effective during operation of the MR attenuator, wherein said damping force vs. main channel MR piston assembly speed curve includes an initial y intercept point and a low main channel A single diagonal ramp ramp that rises generally to the right at MR piston assembly speed follows the single diagonal ramp ramp to an initial knee point on the damping force vs. main channel MR piston assembly speed curve, where the initial knee point is the initial main channel. At the MR piston speed, the initial knee point transitions to a generally gentle right-up diagonal ramp ramp on the damping force vs. main channel MR piston assembly speed curve, which is the initial main channel MR piston assembly. Higher than the initial knee point in speed, or medium Span-high primary channel MR piston assembly velocities, methods.   The step of providing a main channel MR piston assembly further comprises a main channel further including a first main channel portion extending from the second end to the coil groove, the main channel portion being axially connected to the secondary channel. 15. The method of claim 14, wherein the secondary channel length extends from the coil groove to the first end.   The step of providing a main channel MR piston assembly further includes a main channel MR piston assembly including a first substantially magnetic deactivatable MR fluid passage, wherein the first substantially magnetic deactivatable MR fluid passage comprises a piston body. And the first substantially magnetically deactivatable MR fluid passageway defined by the first and second plates therethrough, having a relationship starting from the hole and spaced axially away from the axis The first substantially magnetically deactivatable MR fluid passage is arranged such that the main channel MR piston assembly includes a first damping force vs. main channel MR piston assembly speed curve that is effective during operation of the MR attenuator. The first damping force versus main channel MR piston assembly speed curve includes a first y-intercept point and a first knee point. The first knee point is at the first main channel MR piston assembly speed, the first y intercept point is lower than the initial y intercept point, and the first main channel MR piston assembly speed is Higher than the piston assembly speed, the first knee point is to the right of the initial knee point on the damping force vs. main channel MR piston assembly graph depicting the initial and first damping force vs. main channel MR piston assembly speed curve, The method according to claim 14.   Providing the main channel MR piston assembly further includes setting a width of the main channel and setting a width of the secondary channel substantially equal to the width of the main channel, the width being substantially magnetically energizable MR fluid passage. And increasing the width relative to the length of the substantially magnetically activatable MR fluid passage results in a new damping force vs. main channel MR assembly performance curve, said new performance curve being MR A second y-intercept point and a second knee point are included in the performance operating range of the attenuator, the second knee point being at a second main channel MR piston assembly speed, and the second main channel MR piston speed. 15 is higher than a first main channel MR piston speed and the second y-intercept point is smaller than a first y-intercept point. Law. The method further includes providing a controller, wherein the controller is electrically connected to the main channel MR piston assembly of the MR attenuator, the controller accesses a lookup table that includes a plurality of values, and the values are stored in the lookup table. Said value is used by the controller to operatively control the main channel MR piston assembly of the MR attenuator over the knee point operating range of the main channel MR piston assembly of the MR attenuator;
The value includes a characteristic of at least one of a plurality of predetermined characterized damping force versus main channel MR piston assembly speed curves, wherein the plurality of predetermined characterized damping force versus main channel MR piston assembly speed curves. Said at least one of said plurality of damping forces associated with at least one of a plurality of substantially magnetically deactivatable MR fluid passages defined in said main channel MR piston assembly versus main channel MR piston assembly speed. At least one of a plurality of y-intercept points and at least one of a plurality of knee points representing at least one of the curves, the at least one curve of a plurality of damping force versus main channel MR piston assembly speed curves And the plurality of knee points includes a plurality of main channel MR piston assemblies. At least one of the plurality of y-intercept points is lower than the initial y-intercept point, and at least one of the plurality of main channel MR piston assembly speeds is higher than the main channel MR piston assembly speed. ,
The knee point operating range includes the at least one of an initial damping force versus main channel MR piston assembly speed curve and a plurality of predetermined characterized damping force versus main channel MR piston assembly speed curves;
The controller is
In order to optimize the performance of the main channel MR piston assembly of the MR attenuator during operation of the main channel MR piston assembly of the MR attenuator and at low main channel MR piston assembly speeds,
(I) Of a plurality of predetermined characterized damping forces vs. main channel MR piston assembly speed curves such that the initial damping force vs. main channel MR piston assembly speed curve defines the operation of the main channel MR piston assembly of the MR damper And (ii) at least one of a plurality of predetermined characterized damping force versus main channel MR piston assembly speed curves is a main channel MR piston of the MR attenuator. Configured to electronically select at least one of at least one of a plurality of predetermined characterized damping force versus main channel MR piston assembly speed curves to define the operation of the assembly. 15. The method of claim 14, wherein A magnetic fluid (MR) damping system comprising:
A controller,
At least one ferrofluid (MR) attenuator in electrical connection with the controller, the controller operatively controlling the operation of the MR attenuator;
The MR attenuator includes a longitudinal axis;
A coaxial cylinder in which MR fluid is contained;
A main channel MR piston assembly, wherein the main channel MR piston assembly is coaxially disposed within the cylinder and is adapted to slidably engage within the cylinder for axial reciprocation within the cylinder. Includes a piston body defining a coaxial bore therethrough, the piston body including an outer surface of the body and a first end and a second end axially spaced from the first end; An end and a second end being substantially perpendicular to the axis, and a first end plate attached to the first end and a second end plate attached to the second end;
Around the axis, a circumferential coil groove defined on the outer surface of the main body,
A main channel defined on the outer surface of the body and extending from the hole at the second end to the coil groove;
A conductor disposed in the hole and the main channel and further configured to form an electrical coil disposed in the coil groove;
A non-magnetic material that fills the hole in the main channel and the second end and is configured to effectively seal the conductor and electrical coil therein;
A secondary channel defined on the outer surface of the main body of the piston body and extending from the coil groove toward the first end, wherein the secondary channel is filled with a non-magnetic material, and the piston is centered about the axis. An annular structure that substantially surrounds the body, is attached to the piston body and defines a substantially magnetically energizable MR fluid passage having a relationship parallel to the axis and spaced from the annular space;
Defining a coaxial opening therethrough, and including a coaxial rod attached to the first end plate, wherein the opening in the rod is generally aligned with a hole in the piston body at the first end, and the conductor and electrical Electrically conductive means for connecting,
An MR damping system wherein a primary channel MR piston assembly including a secondary channel defined in the piston body improves MR damping system performance at low primary channel MR piston assembly speeds.   The MR damping system comprises an MR damping suspension system disposed on a device used for transport, wherein the transport device includes at least one wheel, and the at least one MR attenuator is associated with at least one wheel. MR attenuation system according to claim 1.

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